This invention relates to microwave devices, and more particularly to structures for interconnecting between coaxial or coplanar waveguide transmission line and rectangular coaxial transmission line.
A typical technique for providing a vertical RF interconnect with a coaxial line uses hard pins. Hard pin interconnects do not allow for much variation in machine tolerance. Because hard pins rely on solder or epoxies to maintain electrical continuity, visual installation is required, resulting in more variability and less S-Parameter uniformity.
Some interconnect structures employ pin/socket structures. These pin/socket interconnects usually employ sockets which are much larger than the pin they are capturing. This size mismatch may induce reflected RF power in some packaging arrangements. For interconnects to rectangular coaxial transmission line, stripline or similar transmission lines, a pin would have to be soldered onto the surface of the circuit, causing more assembly and repair time.
The transition from coaxial line or coplanar waveguide transmission line to rectangular coaxial transmission line is made with a compressible center conductor. The compressible center conductor is captured within a dielectric, such as REXOLITE (TM), TEFLON (TM), TPX (TM), and allows for a robust, solderless, vertical interconnect. The center conductor in an exemplary embodiment is a thin, gold plated, metal wire (usually tungsten or beryllium copper), which is wound up into a knitted, wire mesh cylinder. The compressible center conductor is captured within the dielectric in such a way as to form a coaxial transmission line.
The compressibility of the center conductor allows for blindmate, vertical interconnects onto rectangular coaxial transmission lines while maintaining a good, wideband RF connection. The compressible center conductor also maintains a good physical contact without the use of solder or conductive epoxies. The RF interconnect can be applied to either side of the circuit board.